Gawd, you're a geek that reads Slashdot. Please invest just a minor amount of effort to learn how a significant new feature from one of the most influential tech companies works. It's not hard - it's been discussed extensively virtually everywhere.

How long does it take to etch a PCB (mould) and how long does it take for gelatine to cool down (finger cast)? (The method that Mythbusters used)

The Mythbusters episode was from 2006, and was done on a sensor that was even older. Technology improves. In a decade, it can improve a lot. Their technique would almost certainly not work today. Apple's sensor requires a pulse, and detects deep skin layers that do not show up on a lifted fingerprint.